In general, washing machines are classified into two types: drum type and pulsator type. As for a drum type washing machine, washing of laundry is performed through drop movements of the laundry as a result of rotating a rotary drum accommodating the laundry therein. In a pulsator type washing machine, on the other hand, washing of the laundry is done by using a friction of water currents generated by rotating a pulsator disposed in a bottom portion of the rotary drum.
Recently, there is an increasing demand for the drum type washing machine because it has many advantages compared to the pulsator type washing machine. For example, by configuring the washing machine as drum type, its capacitance can be greater and the phenomenon of the laundry being entangled with each other can be reduced.
FIG. 1 shows a schematic perspective view of a conventional drum type washing machine and FIG. 2 illustrates a schematic longitudinal cross sectional view thereof. The conventional drum type washing machine includes an approximately box-shaped housing 1; a water tub 2 horizontally or slantingly installed inside the housing 1, for accommodating wash water therein; a rotary drum 3 rotatably installed inside the water tub 2 and provided in its cylindrical portion with a plurality of drum perforations; and a driving motor 4 for rotating the rotary drum 3 to perform a washing and a water-extraction of the laundry.
Formed in front portions of the water tub 2 and the rotary drum 3 are openings through which laundry is loaded into or unloaded from the rotary drum 3. Further, a door 5 is hinged on a front surface of the housing 1 to open or close the opening of the water tub 2. Further, the rotary drum 3 is provided on an inner surface of the cylindrical portion thereof with a plurality of agitation blades 6 that are arranged at a predetermined interval. When the rotary drum 3 rotates, the laundry loaded in the rotary drum 3 is lifted up by the agitation blades 6 and then drops upon reaching a certain height. As these agitation movements are repeated, the laundry is washed.
Installed in an upper portion of the housing 1 are a water supply hose 7 for supplying wash water into the water tub 2 and a detergent dispenser 8 for supplying a detergent to be dissolved in the wash water. Further, a water drain pump 9 for discharging the wash water from the water tub 2 externally is installed in a bottom portion of the housing 1.
Moreover, installed above the water tub 2 is a drying device 20 for drying the laundry by blowing hot air to the laundry in the rotary drum 3. Both end portions of the drying device 20 are connected to communication holes 11 and 12 provided in a front side and a rear side of the water tub 2, respectively. Further, a water jetting nozzle 13 is disposed in a rear portion of the water tub 2 to cool down and dehumidify damp hot air containing therein a great amount of moisture that has evaporated from the laundry while the air flows through the rotary drum 3 thereby making a low-temperature air with low humidify. The air that has passed by the water jetting nozzle 13 is blown into an air flow duct 30 by a rotation of fan 21 and heated by a heater 25 installed inside the air flow duct 30. Then, thus heated high-temperature dry air is redirected into the rotary drum 3.
In this conventional drum type washing machine, however, the hot air for drying the laundry is supplied from the drying device 20 in a direction from the upper portion of the rotary drum 3, on which the air flow duct 30 is installed, toward the lower portion thereof, as illustrated in FIG. 2. And drying hot air is buoyant. So the drying hot air supplied into the rotary drum 3 tends to flow through the upper portion of the rotary drum 3 without contacting the laundry gathered in the lower portion thereof and is discharged from the rotary drum 3 through the drum perforations. Accordingly, the drying of the laundry would become incomplete and drying efficiency would be greatly deteriorated because most of the dry hot air is discharged through the upper portion of the rotary drum without being circulated inside the rotary drum 3 uniformly.